Examining Abundance Anomalies in Globular Cluster Red Giant Stars

Details Examining Abundance Anomalies in Globular Cluster Red Giant Stars Examining Abundance Anomalies in Globular Cluster Red Giant Stars

Dec 1998

adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=1998phdt.........7c&link_type=abstract

Thesis (PHD). UNIVERSITY OF MARYLAND COLLEGE PARK , Source DAI-B 59/06, p. 2800, Dec 1998, 149 pages.

Astronomy and Astrophysics

Astronomy

1

Stellar Evolution, Chemical Abundance

Scientific paper

Due to their old ages and relative isolation, Galactic globular clusters hold the keys to our understanding of many problems in astronomy today. The stars within the clusters were formed during the birth of our Galaxy, and thereby contain a fossil record of the early chemistry of the Galaxy. This in turn allows us to determine their ages, understand the formation history of the Galaxy, and study the evolution of low-mass stars that are chemically different than the sun. However, contrary to the predictions of canonical stellar evolution theory, observations of the brightest red-giant stars have shown that the chemical abundances on their surfaces have been altered over their lifetimes, limiting our ability to study the early Galaxy in general and globular clusters in particular. For example, star-to-star variations of C, N, O, Na, Mg, and Al have been observed in many clusters, despite the fact that most clusters exhibit little variation in the heavier elements. The variations often display a dependence on both the luminosity and metallicity of the star. We approach this problem by combining detailed stellar models in four different red-giant branch (RGB) sequences with an extensive nuclear reaction network. This method allows the effect of the variation in the temperature and density around the hydrogen-burning shell (H shell) of the RGB models on the nuclear reactions to be taken into account. Furthermore, the arrangement of the models into sequences allows for the evolution of the H shell as the models ascend the RGB. In addition, using several sequences of different metallicities allows us to model the range in the observed metallicities of the Galactic globular clusters. Finally, our reaction network operates independently from the stellar evolution code, allowing the effects of the uncertainties in the reaction rates to be followed. Our results qualitatively agree with many of the observed trends and we conclude that most observations can be described in the context of non-standard evolution that involves mixing the nuclearly-processed material from the H shell to the stellar surface.

Affiliated with

Also associated with

No associations

Rating

Examining Abundance Anomalies in Globular Cluster Red Giant Stars does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.

If you have personal experience with Examining Abundance Anomalies in Globular Cluster Red Giant Stars, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Examining Abundance Anomalies in Globular Cluster Red Giant Stars will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFWR-SCP-O-764275